In optical devices, light can be directed and/or manipulated to achieve a desired effect. For example, in an optical device such as an eyepiece used in a virtual reality interface, visible light can be directed and/or manipulated to provide image data that is perceived by a user. Various types of optical devices may be subjected to testing, during and/or after manufacture, to ensure that the devices are manufactured and/or operate according to desired specifications. For example, in some types of optical devices, it may be advantageous to reduce or eliminate the leakage of light out of the device.